The aggregation of sickle cell hemoglobin (HbS) will be studied under a variety of conditions including variable salt concentrations, controlled shear rates, and the presence of chemical inhibitors. The monitoring techniques will be photon correlation spectroscopy (PCS) using infrared radiation, and pulsed field gradient nuclear magnetic resonance (PFG NMR). The time evolution of gelation and the properties of the gels obtained under various conditions will also be determined by sensitive rheological techniques. In particular the elasticity, which has not previously been measured for HbS gels, will be studied. Basic understanding of the aggregation process is sought. Also, it is hoped that the results can be used to predict the types of inhibitors which will be useful in clinical situations.